The purpose of the Child and Adolescent Trial for Cardiovascular Health (CATCH) is to determine the effects of a three-year intervention program of school- and family-based interventions on children's risk for cardiovascular disease. At each of four national sites (California, Louisiana, Minnesota, and Texas), the CATCH project will recruit one cohort of 3rd grade students in 1991-92 in 24 schools and randomize them, after baseline assessment, to one of three conditions: 1) school-based interventions, 2) school- plus family-based interventions, and 3) control and school-based interventions which include three consecutive years of classroom curricula, as well as changes in the school food service, physical education program, and school-wide smoking policies. The primary outcome of interest is cholesterol; secondary outcomes include blood pressure, dietary intake of calories, fat, and sodium, minutes of moderate to vigorous physical activity, and intentions not to use tobacco. It is hypothesized that at post-test, students exposed to the program of interventions, after controlling for baseline values, will have lower cholesterol, lower intake of dietary fat and sodium, and increased physical activity than the control group. It is further hypothesized that the students exposed to the family-based interventions will have more desirable diet patterns than students exposed to the school-based interventions alone. The UCSD CATCH Study Center designed and implemented school, family, and measurement interventions utilizing a multidisciplinary research group with expertise in the study target areas. Phase I, approximately three years in length, was piloted in Vista Unified School District, North County San Diego. The CATCH framework was utilized to select and test the best approaches. Grades 3, 4, and 5 participated in the phased interventions during two years of the pilot study. The final year of Phase I will be spent piloting final revisions in the same school district, based on process evaluations, measurement, and validity studies in San Diego and other collaborating sites. Each of the schools participating have been provided with training, curricula, materials, equipment, and support. CATCH Phase II, four years in length, will utilize all fine-tuned intervention components and will be implemented with a single cohort beginning with third grade classes of school year 1991-92. Excellent relationships, cooperation, and letters of support from several San Diego County School Districts ensure many more than the 24 required elementary schools available to the investigators. The San Diego investigators are experienced in the various strategies that are necessary to maintain robust study group cohorts, crucial to the outcomes of a longitudinal study, in addition to extensive intervention and measurement experience with Spanish- speaking subjects.